20565641 has 4 divisors (see below), whose sum is σ = 21067284. Its totient is φ = 20064000.

The previous prime is 20565637. The next prime is 20565659. The reversal of 20565641 is 14656502.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3168400 + 17397241 = 1780^2 + 4171^2 .

It is a cyclic number.

It is not a de Polignac number, because 20565641 - 2² = 20565637 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20565691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 250760 + ... + 250841.

It is an arithmetic number, because the mean of its divisors is an integer number (5266821).

Almost surely, 2^20565641 is an apocalyptic number.

It is an amenable number.

20565641 is a deficient number, since it is larger than the sum of its proper divisors (501643).

20565641 is an equidigital number, since it uses as much as digits as its factorization.

20565641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 501642.

The product of its (nonzero) digits is 7200, while the sum is 29.

The square root of 20565641 is about 4534.9356114503. The cubic root of 20565641 is about 273.9769858305.

The spelling of 20565641 in words is "twenty million, five hundred sixty-five thousand, six hundred forty-one".